Discharge gap



H. M. TOWNE DISCHARGE GAP Filed July 9, 1940 Fig.5.

Ihventor: I Harold M. Towne, by W 6.

l-hs Attorn ey.

Patented May 12, 1942 DISCHARGE GAP Harold M. Towne, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application July 9, 1940, Serial No. 344,521

7 Claims.

' The present invention relates to discharge gaps and while their use need not necessarily be limited thereto, they are particularly adaptable for protecting insulators of high voltage transmission lines from injury due to arcing between the conductors and earth upon the occurrence of excessive potentials therebetween.

It is an object of the invention to provide a new and improved discharge gap structure which comprises a relatively few parts of simple design and of relatively low manufacturing cost and which may be readily installed upon an insulator of standard design.

These and other objects of the invention will be more particularly described in the following specification taken in connection with the accompanying drawing in which Fig. 1 is a side elevation of an insulator provided with a protective gap structure in accordance with one form of the invention, Fig. 2 is a front elevation of the arrangement, Fig. 3 is a top view thereof, and Fig. 4 is a front view of an insulator provided with a gap structure in accordance witha modification of the invention. Figure 5 shows an alternate fastening for the ground lead.

Referring to Fig. 1, a pin-type insulator Ill is shown mounted upon a metallic supporting bracket II, which bracket is in turn welded to a plate I2 adapted to be secured to a pole l3 by means of lag screws I4. The bracket II is provided with a terminal 15 for the connection of a ground lead l6 thereto.

The gap structure in accordance with the invention comprises a plurality of disk electrodes 20, 2| and 22 supported in a spaced relationship 2 from the surface of the insulator upon arms 23, 24 and 25, respectively. The upper electrode is secured to the line end or cap of the insulator by means of a U-bolt 26, the ends of which bolt extend through cooperating openings in the opposite ends of a cross-piece 21 and to which crosspiece is suitably secured, as by welding, the end of the electrode supporting arm 23. The arm 23 is provided with a terminal 28 for fastening thereto the transmission line indicated at 29.

The intermediate electrode 2I- is secured to an intermediate portion of the insulator ID by an arrangement similar to that provided for the upper electrode 20. The lower electrode supporting arm 25 may be secured in any suitable manner, such as by welding, to the grounded insulator bracket ll.

The electrodes 20, 2| and 22 are secured, as by bolts 32, 33 and 34, respectively, to the bentover ends of the corresponding supporting arms so that the electrodes extend in planes substantially vertical and parallel with planes tangential to the adjacent outer surface of the insulator.

The bolts 32, 33 and 34 extend through cooperat-' ing openings in the respective electrode disks eccentrically of the center thereof so that the spacings between adjacent electrodes may be varied by rotating them upon the ends of their respective supporting arms;

The various electrodes are preferably staggered laterally with respect to each other about the axis of the insulator so that water dripping from the lower edges of the electrodes during freezing temperatures will not form icicles bridging the gaps therebetween. Furthermore, while it is not essential to the practice of the invention to provide a plurality of series gaps, such an arrangement is preferred over a single gap structure so that in the event of a bird alighting on one of the electrodes and short-circuiting one gap an arc-over will not take place during normal line voltage conditions, each gap being so adjusted that it will withstand this voltage.

The electrodes are laterally staggered for the additional reason that the are following flashover will immediately be caused to move upwardly, due to heating and electromagnetic action, along the electrode edges and away from the points of narrowest separation. Burning and pitting of the electrodes atthese points of critical adjustment is minimized while the upwardly moving arc is lengthened due to the upwardly diverging electrode surfaces until broken. Because the electrodes are arranged parallel with the insulator surface, the lengthening arc will at all times be kept a safe distance from insulator as to cause no injury thereto. Furthermore, since the electrodes are circular in shape, the above conditions will hold true regardless of the position of adjustment of the gaps.

Due to the eccentric mounting arrangement of the electrodes the gap spacings may be readily adjusted through a relatively wide range, depending upon the size of the disks and the eccentric location of the bolt holes therethrough. Should a different range of adjustment be desired, the U-bolts clamping theelectrode supports to the insulator may be loosened and the staggered relation of the arms may be varied until the particular gap setting falls within the adjustment range of the electrodes.

In the modification described, the electrodes 20, 2| and 22 are in the'form of circular disks but it will be readily appreciated that the electrodes may merely have adjacent arcuate arcing surfaces not in the form of a true circle. Such electrodes may be pivoted upon the supporting arm eccentrically with respect to such arcuate surfaces whereby an adjustment of the gap spacing may be made by simply pivoting one electrode with respect to the adjacent electrode. It is not necessary that the electrodes comprise solid disks, for in the modification illustrated in Fig. 4 the electrodes 40, M and 42, are shown as comprising rings of a suitable conductor wire. One end of the wire ring is bent back upon itself to form a small loop indicated at 43 for cooperatively receiving the bolt fastening the electrode to the end of the support arm. These rings constitute adjustable eccentrically mounted elec. trodes equivalent to the disk electrodes previously described, but have the advantage of lower cost. 1

The arc gap structure described may be readily installed by any lineman to insulators of standard design and which may already be in service. It is obvious that the lower electrode supporting arm 25 instead of being welded to the insulator bracket ll may be clamped thereto in any suitable manner most convenient for field installation. As shown in Fig. 5, the lower electrode arm 25 may be clamped to the bracket H by means of a U-bolt 45, which may also constitute a terminal for fastening the ground lead I6 thereto.

Having described the principle of operation of my invention in what I consider to be the best embodiments thereof, I'desire to have it understood that the specific modifications shown are merely illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A discharge gapcomprising a pair of substantially circular electrodes, an insulating support for said electrodes, means for adjustably mounting said electrodes eccentrically thereof on said support whereby the spacing between said electrodes may be varied by rotating one of said electrodes relative to the other, said electrodes being arranged in a staggered relation about a substantially vertical axis of said support so that the adjacent circular surfaces of said electrodes diverge upwardly in. all positions of adjustment of said electrodes.

2. A discharge gap comprising a pair of ring electrodes having adjacent arcuate arcing surfaces, relatively insulated supports for said electrodes, means for adjustably mounting said electrodes eccentrically of said surfaces on said supports whereby the spacing between said electrodes may be varied by rotating one of the said electrodes relative to the other, said electrodes being arranged in a staggered relation about a substantially vertical axis of said supports so that the adjacent surfaces of said ring electrodes diverge upwardly in all positions of adjustment of said electrodes.

3. A discharge gap comprising a pair of electrodes, said electrodes having adjacent circular arcing surfaces diverging upwardly with respect to each other, a pair of supports insulated from each other for said electrodes, means for adjustably mounting said electrodes on said supports in a laterally staggered spaced relationship and eccentrically of said circular surfaces whereby the spacing between said adjacent circular surfaces may be varied by rotating one of said electrodes upon its corresponding support, and so that said circular arcing surfaces diverge upwardly in all positions of adjustment of said electrodes.

4. In combination with an insulator, a support for said insulator, protective means for said insulator comprising a first arc gap electrode mounted on the line end of said insulator, a second arc gap electrode secured to said support, said electrodes having adjacent arcuate surfaces, the arcs of said surfaces lying in planes substantially parallel to and spaced from planes tangential to the surface of said insulator, said electrodes being pivotally secured relative to said insulator and said support for eccentric rotation about said arcuate surfaces whereby the spacing between said arcuate surfaces may be varied by rotating one of said electrodes relative to the other. I

5. In combination with an insulator having a grounded support, protective means for said insulator comprising at least three circular electrodes arranged in a staggered relation about the axis of said insulator, means for mounting one of said electrodes upon the line end of said insulator, means for mounting the opposite electrode in a conductive relation upon said grounded support, means for mounting the intermediate electrodes upon intermediate portions of said insulator, the planes of the circles of said electrodes spaced from and extending substantially parallel with planes tangential to the adjacent surface of said insulator, means for pivotally securing said electrodes eccentrically thereof upon the corresponding mounting means whereby the spacing between adjacent electrode surfaces may be varied by rotating said electrodes about said pivotal securing means.

6. In combination with an insulator having a grounded support, protective means for said insulator comprising at least three adjustable arc gap electrodes having arcuate surfaces and arranged in a staggered relation about the axis of said insulator, arms for supporting said elec trodes in a space relation with respect to the adjacent surface of said insulator, means for clamping the arm of one of said electrodes to the line end of said insulator, means for clamping the arm of the opposite electrode in a conductive relation upon said grounded support, means for clamping the arms of intermediate electrodes to intermediate portions of said insulator, said electrodes being so secured upon said arms that said adjacent arcuate surfaces diverge upwardly in all positions of adjustment of said electrodes.

7. In combination with an insulator having a grounded support, protective means for said insulator comprising at least three discharge gap electrodes, arms for supporting said electrodes in a spaced relationship with respect to the adjacent surface of said insulator, means for adjustably clamping the arm of one of said electrodes to the line end of said insulator, means for adjustably securing the opposite electrode in a conductive relation upon said grounded support, means for adjustably securing an intermediate electrode upon an intermediate portion of said insulator, said electrodes having adjacent arcuate arcing surfaces diverging upwardly, and means for pivotally securing said electrodes eccentrically of said arcuate surfaces upon said supporting arms whereby the spacing between adjacent electrode surfaces may be varied by rotating said electrodes about said pivotal securing means.

HAROLD M. TOWNE. 

